If your multipliers are varying like that it means that SpeedStep is enabled. SpeedStep disabled has the CPU run at its maximum frequency constantly. You have an Asus board, some of them are known to automatically overclock the CPUs when using default settings, though I think that is mostly on the enthusiast oriented boards.
In any case you have a good stable overclock so no need to worry about it. That CPU shouldn't have turbo boost, in the BIOS the turbo boost option should either not be there at all, or be greyed out.
Come to think of it, there is no Turbo option at all. So I guess it doesn't have it....
No need to worry then.